The weather looks fine, the astronauts have climbed aboard, and all preparations appear to be going smoothly for today's afternoon launch of space shuttle Atlantis on its mission to repair and upgrade the Hubble Space Telescope. The launch, postponed from last October to deal with electronic problems that arose in September, is scheduled for 2:01 (Eastern Daylight Time) from Kennedy Space Center in Florida.

The seven astronauts on the 11-day mission will deliver new scientific instruments and a slew of replacement parts for Hubble, including a set of new 125-pound (57-kilogram) batteries to replace the six originals that have powered Hubble's night-side activities since its 1990 launch.

The shuttle will also provide Hubble with a new Science Instrument Command and Data Handling (SI C&DH) module; the unit onboard suffered a partial failure in September, leading NASA to push back the servicing mission until a spare could be readied. The critical unit serves as a switchboard for routing commands to Hubble's scientific instruments and relaying data back to Earth. Although engineers on the ground were able to switch to a built-in backup, the unit is now operating without a net, so spacewalkers will install a replacement.

For an in-depth look at what's in store for this mission, see last week's Q&A with Hubble senior project scientist David Leckrone of the NASA Goddard Space Flight Center in Greenbelt, Md. And check back in the afternoon as we update the mission's progress after launch. In the meantime, for up-to-the-minute reports on the shuttle's preparation for liftoff, follow NASA on Twitter.

Photo of Atlantis on launch pad at Kennedy Space Center: NASA Television